Re: questions on using the array component iterator for 2012

[Shark8 <onewingedshark@gmail.com>]

On Saturday, June 23, 2012 7:02:18 AM UTC-5, Nasser M. Abbasi wrote:
> For example, assume I write
>     FOR e of A  LOOP
>         e := e + 1 ;
>     END LOOP
> [...]
> 
> But suppose I want to implement say a Jacobi relaxation
> iteration to solve a 2D Laplace pde on that grid, which
> is defined to update each element in the grid using
> 
> A(i,j) := (1/4) (  A(i-1,j)+A(i+1,j)+A(i,j-1)+A(i,j+1)
> 
> where here 'i' is row index, and 'j' is column index.

Well the problem is that the "FOR E IN ..." loop is conceptually different from a "FOR Index IN Array_Variable'RANGE" loop. The difference is that in the former you don't care what the index/indices are, you just want to apply the same procedure to each element.

Given that needing the index is sometimes wanted, the designers may have added a 'Index(X) attribute, I don't really know because I've not had the inclination to explore the new loop in such depth.